Medical instruments for endoscopic surgery generally have a hollow shaft, at the proximal end of which a handle is arranged, and at the distal end of which a tool is arranged that is composed of two jaw parts movable relative to each other. The tool, designed as a gripping, holding and/or cutting instrument, can be actuated via the handle. To be able to provide the greatest possible range of action within the often confined working conditions in which the tool is used, many endoscopic instruments are designed such that the tool can be angled with respect to the longitudinal axis of the shaft and also such that the tool is rotatable about the longitudinal axis of the shaft.
A problem presented by the medical instruments known from the prior art, with these numerous possible adjustments of the tool tip and/or of the distal tool, is that the angled positioning of the tool tip relative to the proximal shaft region results in a forced movement of the jaw parts relative to each other and/or a rotation movement of the tool tip. To deal with this forced movement, various elaborate compensation mechanisms are known in practice. Although these compensation mechanisms ensure that the tool tip can be angled in a manner substantially free from forced movement, the structure is very complex and runs counter to the compact configuration that is required particularly in endoscopic instruments.
A medical instrument of the type in question is known, for example, from DE 103 14 823 B3. In this known surgical instrument, a movement compensation element is provided which ensures that a rotation caused by the angled positioning of the tool tip is compensated.